differentiate between the characteristics, composition, and location of comets, asteroids, and meteoroids.

Asteroids

At first glance, asteroids may seem like run-of-the-mill space rocks, but these ancient solar system remnants come in all shapes, sizes and flavors

Comets

For millennia, the sight of a comet elicited fear and awe. Ancient astronomers believed comets foretold the death of princes and the outcomes of wars. Modern astronomers know comets are the ice-clad leftovers from the material that formed our solar system billions of years ago.

Meteoroids

Meteoroids are the true space rocks of the solar system. No larger than a meter in size (3.3 feet) and sometimes the size of a grain of dust, they are too small to be considered asteroids or comets, but many are the broken pieces of either. Some meteoroids originate from the ejected debris caused by impacts on planets or moons.

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.